A brake is a device that is included in automotive vehicles to inhibit motion. Brakes commonly use friction to convert kinetic energy into heat, though other methods of energy conversion may be employed. For example, regenerative braking converts much of the kinetic energy to electric energy, which may be stored for later use.
On vehicles, braking systems are employed to apply a retarding force, typically via frictional elements at the vehicle's rotating axles or wheels, to inhibit vehicle motion. Friction brakes often include stationary shoes or pads that are lined with friction material and configured to be applied against a rotating wear surface, such as a rotor or a drum. Common configurations include shoes that contact to rub on the outside of a rotating drum, commonly called a “band brake,” a rotating drum with shoes that expand to rub the inside of a drum, commonly called a “drum brake,” and pads that pinch a rotating disc, commonly called a “disc brake.”
Another form of braking involves applying a torque that is counter to the direction of rotation of the wheel using an electric motor. In effect, the inertia of the vehicle drives the electric motor in reverse. Doing so then causes the inertial torque to drive the motor as a generator, which can regenerate the vehicle batteries, while simultaneously slowing the vehicle. As such this form of braking is often referred to as regenerative braking.